1. Field of the Invention
Embodiments of the invention generally relate to the field of spectrometers, and more specifically to Sagnac interferometer spectrometers.
2. Description of the Related Art
In a Sagnac interferometer, an input light is split into two beams that follow, for example, a ring trajectory in opposite directions. The input light can be split using, for example, a beamsplitter. The two beams, commonly called clockwise and counterclockwise beams or transmitted and reflected beams, can be made to have slight propagation variations. The transmitted and reflected beams can then be recombined by the beamsplitter, at which point such propagation variations can be manifested in effects such as interference patterns. Information about the propagation variations can be measured by, for example, analyzing the interference pattern created by the recombined beams.
In a Sagnac interference spectrometer, one or more diffraction gratings can be included in the optical path of the counter-propagating beams. Dispersion in the grating(s) alters the propagation direction of the two beams, shifting one with respect to the other. The shift in the beams is manifested by a variation in the resultant interference pattern. This interference pattern can be processed to determine the spectral characteristics of the counter-propagating beams. For example, a Fourier transform of the interference pattern yields the wavelength spectra of the beams.